This invention relates to pallets for transporting and storing yarn bobbins wound on cylindrical tubes, and is more particularly concerned with a lightweight plastic pallet which can be molded as one integral unit and is suitable for reuse.
In transporting yarn bobbins, the bobbins must be kept immobilized and separated from each other in order to prevent impact or rubbing contact which would damage the yarn or cause it to slip off of the carrier. Any distortion of the winding pattern or snarling of the yarn may be considered to be unacceptable by a customer.
Numerous pallets have been devised to provide a spaced and immobile arrangement of tiers of tubular or cone-shaped yarn bobbins. Pallets constructed of many kinds of materials with various types of holding or centering members have been proposed. Such prior art solutions included dividers fabricated from cardboard, papier-mache or paper pulp. Although pallets of such materials are economical, they do not readily lend themselves to reuse. Pallets composed of steel rods and stamped sheet metal holding members proved reusable but highly expensive to manufacture. Neubert U.S. Pat. No. 3,730,340 dated May 1, 1973, proposes the improvement of molding plastic holding members in two parts which snap together about the intersections of rods. This construction is somewhat more economical but is still expensive in comparison to a pallet molded entirely of plastic in a single operation. Furthermore, although empty pallets can be stacked for reuse by inserting protuberances on one pallet partially into protuberances on another pallet, this can only be done when the proper faces of the pallets are brought together and, even then, the pallets will not be closely stacked.
Pallets of tough molded plastic which are light-weight, inexpensive to manufacture, and can be reused many times have been disclosed in Sibille U.S. Pat. No. 3,335,858 dated Aug. 15, 1967, and Schlager et al. U.S. Pat. No. 3,375,919 dated Apr. 2, 1968. However, a notable deficiency of such prior molded plastic pallets is that the pallets are constructed to nest only when loaded with bobbin tubes. The customer is unable to assemble empty pallets in a neat stack for return to the supplier.